Integrated circuits have evolved into enormously complex devices, which are fabricated by equally complex processes. As the term is used herein, “integrated circuit” includes devices such as those formed on monolithic semiconducting substrates, such as those formed of group IV materials like silicon or germanium, or group III-V compounds like gallium arsenide, or mixtures of such materials. The term includes all types of devices formed, such as memory and logic, and all designs of such devices, such as MOS and bipolar. The term also comprehends applications such as flat panel displays, solar cells, and charge coupled devices.
Integrated circuits are typically processed in a wafer form on a common semiconducting substrate, which substrate typically holds something in the neighborhood of a few hundred individual integrated circuits, depending on die size and wafer size. A variety of information on the processing of the substrate is typically recorded in a database. Thus, while the integrated circuits are in wafer form, it is relatively easy to look back upon the recorded processing history for the integrated circuits, by first identifying the substrate upon which the integrated circuits reside, and then accessing the information for the substrate. Such information can be very useful in determining the causes of problems that might be noticed at a later point in the fabrication cycle.
However, once the individual integrated circuits are singulated and packaged, it might be impossible to determine the substrate from which a given integrated circuit was taken, and the processing that the substrate received. However, for a variety of different reasons, such information could be extremely useful. For example, determining the processing given an integrated circuit that failed in the field could help prevent additional future failures for the same cause.
What is needed, therefore, is a system that overcomes problems such as those described above, at least in part.